[Kju]

Hello, i got this problem:

Im having a 4 down & 0.5 upload connection, which is more then enough if it's stable.
Yet, I've realised that right after im plugging my ethernet cable to the PC, the speed drops a lot, mostly download. It goes from 4.1 / 0.5 to 0.1 / 0.3.
Im using win10 & checked on the resource monitor what is taking up my network speed on the PC. Yet, there are just the usual programs showing up which im using since years & they didn't had any update recently (online game & ts3). Even right after just starting my PC, not running any program, i can see the download speed graph dropping hard. Im making a speedtest at the same time on my smartphone via the speedtest app. Once i unplug it, the speed goes back to 4.1 /0.5.
I've aswell checked my PC on malware and found nothing (Using Avira). Was thinking that i may have a virus or smth which tries to connect or whatever.
My technical provider changed all the connections and ports already & can't find any mistake.

It's really strange, since sometimes the speed, even while connected to the PC is normal and out of nothing it drops like explained.

Thanks in forward for any helpfull answers & tips